15
6.1
Examples
A Read Register Request to read holding register address 100 of Slave 01
(undefined address for Slave, beyond address limit).
Register Register
Number
Number
Error
Start
Start
of
of
Check
Address
Function
Offset
Offset
Registers
Registers
Field
(CRC-16)
High
Low
High
Low
01
03
00
FA
00
06
E5
F9
The slave replies with an exception response signifying an ‘illegal data address’. To
indicate that the response is a notification of an error, the most significant bit of the
function code is set to 1.
Slave Address
Function
Exception
Error Check
(CRC-16)
01
83
02
C0
F1
6
EXCEPTION RESPONSES
Table 6.1 Exception Response Codes
The exception response codes sent by the slave are shown in Table 6.1. When a
slave detects one of these errors, it sends a response message to the master
consisting of slave address, function code, error code and error check fields.
Exception
Response
Code
Exception Response
Name
Exception Response
Definition
Illegal
Function
Illegal
Data Address
Illegal
Data Value
Negative
Acknowledgement
Memory
Parity Error
The message function received is not an allowable
function on the COMMANDER 100/150/160/V100.
The address reference in the data field is not an allowable
address for the COMMANDER 100/150/160/V100.
The value referenced in the data field is not allowable
in the addressed slave location.
The function just requested cannot be performed.
Parity check indicates an error in one or more of the
characters received.
01
02
03
07
08
